JP7506479B2 - Austenitic stainless steel material, its manufacturing method, and electronic device component - Google Patents
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- 239000000463 material Substances 0.000 title claims description 75
- 229910000963 austenitic stainless steel Inorganic materials 0.000 title claims description 64
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- 238000005096 rolling process Methods 0.000 claims description 29
- 238000005098 hot rolling Methods 0.000 claims description 20
- 229910052757 nitrogen Inorganic materials 0.000 claims description 13
- 239000010960 cold rolled steel Substances 0.000 claims description 10
- 239000012535 impurity Substances 0.000 claims description 10
- 229910052799 carbon Inorganic materials 0.000 claims description 9
- 238000005097 cold rolling Methods 0.000 claims description 8
- 229910052758 niobium Inorganic materials 0.000 claims description 6
- 238000000137 annealing Methods 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000012360 testing method Methods 0.000 description 16
- 229910000859 α-Fe Inorganic materials 0.000 description 12
- 206010039509 Scab Diseases 0.000 description 10
- 229910000734 martensite Inorganic materials 0.000 description 9
- 229910000831 Steel Inorganic materials 0.000 description 8
- 238000011156 evaluation Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 239000010959 steel Substances 0.000 description 8
- 230000007547 defect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 230000001965 increasing effect Effects 0.000 description 6
- 230000005389 magnetism Effects 0.000 description 6
- 230000035699 permeability Effects 0.000 description 6
- 230000009467 reduction Effects 0.000 description 6
- 229910052802 copper Inorganic materials 0.000 description 5
- 229910052748 manganese Inorganic materials 0.000 description 5
- 229910017566 Cu-Mn Inorganic materials 0.000 description 4
- 229910017871 Cu—Mn Inorganic materials 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 4
- 229910052750 molybdenum Inorganic materials 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 238000009864 tensile test Methods 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 230000005415 magnetization Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000005554 pickling Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
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- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
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Description
本発明は、オーステナイト系ステンレス鋼材及びその製造方法、並びに電子機器部材に関する。 The present invention relates to an austenitic stainless steel material, a manufacturing method thereof, and an electronic device component.
電子機器部材（例えば、筐体、部品など）に使用されるステンレス鋼材には、磁化され難い性質が要求されることが多い。また、近年では、電子機器部材の小型化及び軽量化に伴い、電子機器部材に使用されるステンレス鋼材にも薄肉化の要求が高まっている。これらの要求に対応するためには、磁化され難い性質に加え、強度、延性及びばね性に優れることがステンレス鋼材に望まれている。 Stainless steel materials used in electronic equipment components (e.g., housings, parts, etc.) are often required to be resistant to magnetization. In recent years, as electronic equipment components have become smaller and lighter, there has been an increasing demand for thinner stainless steel materials used in electronic equipment components. To meet these demands, stainless steel materials are desired to have excellent strength, ductility, and spring properties in addition to being resistant to magnetization.
磁化され難い性質に関する要求レベルとしては、用途に応じて非磁性（μ≦１．０１）と低磁性（１．０１＜μ≦１．１０）とに大別される。
非磁性の用途には、Ｎｉ含有量を高めて加工誘起マルテンサイト相が生成しないように成分設計されたオーステナイト系ステンレス鋼材（ＳＵＳ３０５系など）が一般に使用されている。なお、非磁性の用途に使用可能なオーステナイト系ステンレス鋼材は、磁気特性のみに着目すれば、低磁性の用途にも使用可能である。しかしながら、一般に非磁性のオーステナイト系ステンレス鋼材は原料コストが高く、ばね性も十分でない。
The required level of resistance to magnetization is roughly divided into non-magnetic (μ≦1.01) and low magnetic (1.01<μ≦1.10) depending on the application.
For non-magnetic applications, austenitic stainless steel materials (such as SUS305 series) are generally used, which are designed to have a high Ni content so as not to produce a processing-induced martensite phase. Note that austenitic stainless steel materials usable for non-magnetic applications can also be used for low-magnetic applications if attention is focused only on magnetic properties. However, non-magnetic austenitic stainless steel materials generally have high raw material costs and insufficient spring properties.
一方、低磁性の用途には、Ｎ含有量を高めたりＣｕを添加したりする手法によって加工誘起マルテンサイト相の生成量を抑制したオーステナイト系ステンレス鋼材（ＳＵＳ３０４系など）や、多量のＭｎを添加したオーステナイト系ステンレス鋼材などが知られている。しかしながら、既存の低磁性のオーステナイト系ステンレス鋼材では、強度、延性及びばね性を同時に満足することは困難である。 On the other hand, for low magnetic applications, austenitic stainless steel materials (such as SUS304 series) that suppress the formation of processing-induced martensite phase by increasing the N content or adding Cu, and austenitic stainless steel materials with large amounts of Mn added are known. However, it is difficult for existing low magnetic austenitic stainless steel materials to simultaneously satisfy the requirements for strength, ductility, and spring properties.
非磁性又は低磁性の用途に使用可能なオーステナイト系ステンレス鋼材の強度やばね性などの各種特性を改善するために、特許文献１～４には、様々な組成を有するオーステナイト系ステンレス鋼材が提案されている。 In order to improve various properties such as strength and springiness of austenitic stainless steel materials that can be used for non-magnetic or low-magnetic applications, Patent Documents 1 to 4 propose austenitic stainless steel materials with various compositions.
しかしながら、上記の特許文献に開示のオーステナイト系ステンレス鋼材は、非磁性のオーステナイト系ステンレス鋼材と同程度のレベルのばね性しか有しておらず、薄肉化の要求に対応するばね性を満足できないことがある。
また、上記の特許文献に開示のオーステナイト系ステンレス鋼材は、所定の組成を有するスラブを熱間圧延した後、冷間圧延することによって製造されているものの、熱間加工性が低いため、熱間圧延時に表面にヘゲ疵や板幅方向端部に耳割れなどの欠陥が生じ易い。このような欠陥は、歩留りの低下、後工程の負荷及び製造コストの増大をもたらすだけでなく、製品特性を低下させる要因となる。そのため、これらの欠陥の発生を抑制するために、２ヒート圧延（約８５０℃の低温で分塊圧延を行った後に仕上圧延を行う圧延）によって熱間圧延を行う必要があり、生産性が低い。
However, the austenitic stainless steel materials disclosed in the above patent documents only have a level of springiness equivalent to that of non-magnetic austenitic stainless steel materials, and may not be able to satisfy the springiness required for thinner walls.
In addition, the austenitic stainless steel material disclosed in the above patent document is manufactured by hot rolling a slab having a predetermined composition and then cold rolling it, but since the hot workability is low, defects such as scabs on the surface and edge cracks on the ends in the width direction of the plate are likely to occur during hot rolling. Such defects not only reduce the yield, increase the load on the subsequent processes and the manufacturing cost, but also cause deterioration of product characteristics. Therefore, in order to suppress the occurrence of these defects, it is necessary to perform hot rolling by two-heat rolling (rolling in which blooming is performed at a low temperature of about 850°C and then finish rolling is performed), which results in low productivity.
本発明は、上記のような問題を解決するためになされたものであり、低磁性又は非磁性であるとともに、強度、延性及びばね性に優れ、しかも生産性が高いオーステナイト系ステンレス鋼材及びその製造方法を提供することを目的とする。
また、本発明は、小型化及び軽量化が可能な電子機器部材を提供することを目的とする。
The present invention has been made to solve the above-mentioned problems, and has an object to provide an austenitic stainless steel material which is low magnetic or non-magnetic, has excellent strength, ductility and springiness, and is highly productive, and a method for manufacturing the same.
Another object of the present invention is to provide an electronic device component that can be made smaller and lighter.
本発明者らは、上記のような問題を解決すべく鋭意研究を行った結果、オーステナイト系ステンレス鋼材の組成、ＭＤ値及びδｃａｌ値を制御することにより、低磁性又は非磁性としつつ、強度、延性及びばね性を高めることができ、しかも熱間加工性の向上によって１ヒート圧延による熱間圧延が可能になることを見出し、本発明を完成するに至った。 The inventors conducted extensive research to solve the above problems and discovered that by controlling the composition, MD value, and δcal value of austenitic stainless steel material, it is possible to improve the strength, ductility, and spring properties while making it low magnetic or non-magnetic, and that the improvement in hot workability makes it possible to perform hot rolling in one heat rolling, thus completing the present invention.
すなわち、本発明は、Ｃ：０．０９５質量％超過０．１６０質量％以下、Ｓｉ：０．２０～１．２０質量％、Ｍｎ：２．００～６．００質量％、Ｎｉ：２．５０～６．００質量％、Ｃｒ：１４．００～１９．５０質量％、Ｎ：０．０９０～０．２１０質量％、Ｃｕ：０．５０～３．６０質量％、Ｍｏ：０．１０～１．５０質量％、Ｃａ：０．００１０～０．０１５０質量％を含み、残部がＦｅ及び不可避的不純物からなり、Ｃ及びＮの合計含有量が０．２５質量％以上、下記式（１）で表されるＭＤ値が－７０以下、及び下記式（２）で表されるδｃａｌ値が－１１～３．２０であるオーステナイト系ステンレス鋼材である。
ＭＤ＝５５１－４６２（Ｃ＋Ｎ）－９．２Ｓｉ－１９．１Ｍｎ－２９（Ｎｉ＋Ｃｕ）－１３．７Ｃｒ－１８．５Ｍｏ （１）
δｃａｌ＝－１５－４４．９１Ｃ－０．８８Ｍｎ－２．３１Ｎｉ＋２．２Ｃｒ－１．０８Ｃｕ－２８．８Ｎ （２）
式（１）及び（２）中、各元素記号は各元素の含有量（質量％）である。
That is, the present invention is an austenitic stainless steel material containing C: more than 0.095 mass% and 0.160 mass% or less, Si: 0.20 to 1.20 mass%, Mn: 2.00 to 6.00 mass%, Ni: 2.50 to 6.00 mass%, Cr: 14.00 to 19.50 mass%, N: 0.090 to 0.210 mass%, Cu: 0.50 to 3.60 mass%, Mo: 0.10 to 1.50 mass%, Ca: 0.0010 to 0.0150 mass%, with the balance being Fe and unavoidable impurities, the total content of C and N is 0.25 mass% or more, the MD value represented by the following formula (1) is -70 or less, and the δcal value represented by the following formula (2) is -11 to 3.20 .
MD = 551 - 462 (C + N) - 9.2 Si - 19.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo (1)
δcal = -15-44.91C-0.88Mn-2.31Ni+2.2Cr-1.08Cu-28.8N (2)
In formulas (1) and (2), each element symbol represents the content (mass %) of each element.
また、本発明は、Ｃ：０．０９５質量％超過０．１６０質量％以下、Ｓｉ：０．２０～１．２０質量％、Ｍｎ：２．００～６．００質量％、Ｎｉ：２．５０～６．００質量％、Ｃｒ：１４．００～１９．５０質量％、Ｎ：０．０９０～０．２１０質量％、Ｃｕ：０．５０～３．６０質量％、Ｍｏ：０．１０～１．５０質量％、Ｃａ：０．００１０～０．０１５０質量％を含み、残部がＦｅ及び不可避的不純物からなり、Ｃ及びＮの合計含有量が０．２５質量％以上、下記式（１）で表されるＭＤ値が－７０以下、及び下記式（２）で表されるδｃａｌ値が－１１～３．２０であるスラブを１１８０℃以上に加熱して１ヒート圧延する熱間圧延を行うオーステナイト系ステンレス鋼材の製造方法である。
ＭＤ＝５５１－４６２（Ｃ＋Ｎ）－９．２Ｓｉ－１９．１Ｍｎ－２９（Ｎｉ＋Ｃｕ）－１３．７Ｃｒ－１８．５Ｍｏ （１）
δｃａｌ＝－１５－４４．９１Ｃ－０．８８Ｍｎ－２．３１Ｎｉ＋２．２Ｃｒ－１．０８Ｃｕ－２８．８Ｎ （２）
式（１）及び（２）中、各元素記号は各元素の含有量（質量％）である。
The present invention also includes C: more than 0.095 mass% and 0.160 mass% or less, Si: 0.20 to 1.20 mass%, Mn: 2.00 to 6.00 mass%, Ni: 2.50 to 6.00 mass%, Cr: 14.00 to 19.50 mass%, N: 0.090 to 0.210 mass%, Cu: 0.50 to 3.60 mass%, Mo: 0.10 to 1.50 mass%, Ca: 0.0010 to 0.0150 mass%, the balance being Fe and unavoidable impurities. The total content of C and N is 0.25 mass% or more, the MD value represented by the following formula (1) is -70 or less, and the δcal value represented by the following formula (2) is -11 to 3.20. This is a method for producing an austenitic stainless steel material, in which a slab is heated to 1180 ° C. or more and hot-rolled for one heat.
MD = 551 - 462 (C + N) - 9.2 Si - 19.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo (1)
δcal = -15-44.91C-0.88Mn-2.31Ni+2.2Cr-1.08Cu-28.8N (2)
In formulas (1) and (2), each element symbol represents the content (mass %) of each element.
また、本発明は、前記オーステナイト系ステンレス鋼材から形成される電子機器部材である。 The present invention also relates to an electronic device component formed from the austenitic stainless steel material.
本発明によれば、低磁性又は非磁性であるとともに、強度、延性及びばね性に優れ、しかも生産性が高いオーステナイト系ステンレス鋼材及びその製造方法を提供することができる。
また、本発明によれば、小型化及び軽量化が可能な電子機器部材を提供することができる。
According to the present invention, it is possible to provide an austenitic stainless steel material which is low magnetic or non-magnetic, has excellent strength, ductility and springiness, and is highly productive, and a method for producing the same.
Furthermore, according to the present invention, it is possible to provide an electronic device member that can be made smaller and lighter.
以下、本発明の実施形態について具体的に説明する。本発明は以下の実施形態に限定されるものではなく、本発明の趣旨を逸脱しない範囲で、当業者の通常の知識に基づいて、以下の実施形態に対し変更、改良などが適宜加えられたものも本発明の範囲に入ることが理解されるべきである。 The following is a detailed description of the embodiments of the present invention. The present invention is not limited to the following embodiments, and it should be understood that modifications and improvements to the following embodiments, as appropriate, based on the ordinary knowledge of those skilled in the art, fall within the scope of the present invention, provided they do not deviate from the spirit of the present invention.
本発明の実施形態に係るオーステナイト系ステンレス鋼材は、Ｃ：０．０９５質量％超過０．１６０質量％以下、Ｓｉ：０．２０～１．２０質量％、Ｍｎ：２．００～６．００質量％、Ｎｉ：２．５０～６．００質量％、Ｃｒ：１４．００～１９．５０質量％、Ｎ：０．０９０～０．２１０質量％、Ｃｕ：０．５０～３．６０質量％、Ｍｏ：０．１０～１．５０質量％、Ｃａ：０．０００５～０．０１５０質量％を含み、残部がＦｅ及び不可避的不純物からなる。
また、本発明の実施形態に係るオーステナイト系ステンレス鋼材は、必要に応じて、Ｖ：０．３５質量％以下、Ｎｂ：０．３５質量％以下及びＴｉ：０．３５質量％以下から選択される少なくとも１種を更に含んでもよい。
ここで、本明細書において「不可避的不純物」とは、Ｏ、Ｐ、Ｓ、Ａｌ、希土類（ＲＥＭ）、Ｂなどの、スクラップ原料や電気炉、取鍋などから混入して除去することが難しい成分のことを意味する。不可避的不純物は、原料を溶製する段階で不可避的に混入する。通常、Ｐは０．０６０質量％以下、Ｓは０．０１０質量％以下である。
The austenitic stainless steel material according to an embodiment of the present invention contains C: more than 0.095 mass% and 0.160 mass% or less, Si: 0.20 to 1.20 mass%, Mn: 2.00 to 6.00 mass%, Ni: 2.50 to 6.00 mass%, Cr: 14.00 to 19.50 mass%, N: 0.090 to 0.210 mass%, Cu: 0.50 to 3.60 mass%, Mo: 0.10 to 1.50 mass%, Ca: 0.0005 to 0.0150 mass%, and the balance being Fe and unavoidable impurities.
Furthermore, the austenitic stainless steel material according to the embodiment of the present invention may further contain at least one selected from V: 0.35 mass% or less, Nb: 0.35 mass% or less, and Ti: 0.35 mass% or less, as necessary.
In this specification, the term "unavoidable impurities" refers to components such as O, P, S, Al, rare earth elements (REM), and B that are mixed in from scrap raw materials, electric furnaces, ladles, etc. and are difficult to remove. The inevitable impurities are mixed in unavoidably at the stage of melting the raw materials. Usually, P is 0.060 mass% or less, and S is 0.010 mass% or less.
Ｃは、オーステナイト系ステンレス鋼材の磁性、強度、延性及びばね性に影響を与える極めて重要な元素である。オーステナイト系ステンレス鋼材を低磁性又は非磁性とし、且つ強度、延性及びばね性を向上させるためには、Ｃ含有量を０．０９５質量％超過、好ましくは０．１００質量％以上とする。また、オーステナイト系ステンレス鋼材を冷延鋼板とする場合、最終的な冷間圧延（以下、「調質圧延」という）において良好な延性向上作用を安定して実現するためには、Ｃ含有量を０．０９５質量％超過とすることが非常に有効である。一方、Ｃ含有量が多すぎると、オーステナイト系ステンレス鋼材が過度に硬化し、加工性を害するようになる。そのため、Ｃ含有量を０．１６０質量％以下、好ましくは０．１５５質量％以下とする。 C is an extremely important element that affects the magnetism, strength, ductility, and springiness of austenitic stainless steel materials. In order to make austenitic stainless steel materials low magnetic or non-magnetic and improve their strength, ductility, and springiness, the C content is set to more than 0.095 mass%, preferably 0.100 mass% or more. In addition, when the austenitic stainless steel material is made into a cold-rolled steel sheet, it is very effective to set the C content to more than 0.095 mass% in order to stably achieve a good ductility improvement effect in the final cold rolling (hereinafter referred to as "temper rolling"). On the other hand, if the C content is too high, the austenitic stainless steel material will be excessively hardened, impairing its workability. Therefore, the C content is set to 0.160 mass% or less, preferably 0.155 mass% or less.
Ｓｉは、オーステナイト系ステンレス鋼材を高強度化するのに有効な元素である。また、Ｓｉは、脱酸剤として使用される元素でもある。これらの作用を得るために、Ｓｉ含有量を０．２０質量％以上、好ましくは０．３０質量％以上、より好ましくは０．４０質量％以上とする。一方、オーステナイト系ステンレス鋼材を低磁性又は非磁性とするために、Ｓｉ含有量を１．２０質量％以下、好ましくは１．１０質量％以下とする。 Si is an element that is effective in increasing the strength of austenitic stainless steel materials. Si is also an element that is used as a deoxidizer. To obtain these effects, the Si content is set to 0.20 mass% or more, preferably 0.30 mass% or more, and more preferably 0.40 mass% or more. On the other hand, to make the austenitic stainless steel material low magnetic or non-magnetic, the Si content is set to 1.20 mass% or less, and preferably 1.10 mass% or less.
Ｍｎは、オーステナイト相の安定化元素である。オーステナイト系ステンレス鋼材を低磁性又は非磁性とするためには、Ｍｎ含有量を２．００質量％以上、好ましくは３．００質量％以上とする。一方、Ｍｎ含有量が多すぎると、熱間加工性や低温靭性が低下する。そのため、Ｍｎ含有量を６．００質量％以下、好ましくは５．５５質量％以下とする。 Mn is an element that stabilizes the austenite phase. To make an austenitic stainless steel material low magnetic or non-magnetic, the Mn content is set to 2.00 mass% or more, preferably 3.00 mass% or more. On the other hand, if the Mn content is too high, the hot workability and low-temperature toughness decrease. Therefore, the Mn content is set to 6.00 mass% or less, preferably 5.55 mass% or less.
Ｎｉは、オーステナイト系ステンレス鋼材の基本成分である。オーステナイト系ステンレス鋼材を低磁性又は非磁性とするためには、Ｎｉ含有量を２．５０質量％以上、好ましくは３．００質量％以上とする。一方、Ｎｉ含有量が多すぎると、強度の上昇作用が小さくなる。そのため、Ｎｉ含有量を６．００質量％以下、好ましくは５．９０質量％以下とする。 Ni is a basic component of austenitic stainless steel materials. To make austenitic stainless steel materials low magnetic or non-magnetic, the Ni content is set to 2.50 mass% or more, preferably 3.00 mass% or more. On the other hand, if the Ni content is too high, the strength increasing effect is reduced. Therefore, the Ni content is set to 6.00 mass% or less, preferably 5.90 mass% or less.
Ｃｒは、オーステナイト系ステンレス鋼材の耐食性を担う基本成分である。オーステナイト系ステンレス鋼材の耐食性を十分に確保するためには、Ｃｒ含有量を１４．００質量％以上、好ましくは１５．００質量％以上とする。一方、Ｃｒ含有量が多すぎると、δフェライト相が生成し易くなり、低磁性又は非磁性とすることができなくなる。そのため、Ｃｒ含有量を１９．５０質量％以下、好ましくは１９．００質量％以下とする。 Cr is a basic component that is responsible for the corrosion resistance of austenitic stainless steel materials. In order to ensure sufficient corrosion resistance of austenitic stainless steel materials, the Cr content is set to 14.00 mass% or more, preferably 15.00 mass% or more. On the other hand, if the Cr content is too high, the δ ferrite phase is easily generated, making it impossible to achieve low magnetic or non-magnetic properties. Therefore, the Cr content is set to 19.50 mass% or less, preferably 19.00 mass% or less.
Ｎは、オーステナイト相の安定化元素である。また、Ｎは、オーステナイト系ステンレス鋼材を低磁性又は非磁性としつつ高強度化を図る上で重要な元素である。これらの作用を十分に発揮させるためには、Ｎ含有量を０．０９０質量％以上、好ましくは０．０９５質量％以上、より好ましくは０．１００質量％以上とする。一方、Ｎ含有量が多すぎると、オーステナイト系ステンレス鋼材の延性が低下する要因となる。そのため、Ｎ含有量を０．２１０質量％以下、好ましくは０．２００質量％以下とする。 N is an element that stabilizes the austenitic phase. In addition, N is an important element in making austenitic stainless steel material low magnetic or non-magnetic while increasing its strength. In order to fully exert these effects, the N content is set to 0.090 mass% or more, preferably 0.095 mass% or more, and more preferably 0.100 mass% or more. On the other hand, if the N content is too high, it can cause a decrease in the ductility of the austenitic stainless steel material. Therefore, the N content is set to 0.210 mass% or less, preferably 0.200 mass% or less.
Ｃｕは、オーステナイト相の安定化元素である。オーステナイト系ステンレス鋼材を低磁性又は非磁性とするためには、Ｃｕ含有量を０．５０質量％以上、好ましくは０．６０質量％以上とする。一方、Ｃｕ含有量が多すぎると、熱間加工性が低下する要因となる。そのため、Ｃｕ含有量を３．６０質量％以下、好ましくは３．５０質量％以下とする。 Cu is an element that stabilizes the austenite phase. To make an austenitic stainless steel material low magnetic or non-magnetic, the Cu content is set to 0.50 mass% or more, preferably 0.60 mass% or more. On the other hand, if the Cu content is too high, it can cause a decrease in hot workability. Therefore, the Cu content is set to 3.60 mass% or less, preferably 3.50 mass% or less.
Ｍｏは、オーステナイト系ステンレス鋼材の耐食性及び加工硬化性の向上に有効な元素である。これらの作用を十分に得るために、Ｍｏ含有量を０．１０質量％以上、好ましくは０．１５質量％以上とする。一方、Ｍｏ含有量が多すぎると、δフェライト相が生成し易くなり、低磁性又は非磁性とすることができなくなる。そのため、Ｍｏ含有量を１．５０質量％以下、好ましくは１．４５質量％以下とする。 Mo is an element that is effective in improving the corrosion resistance and work hardening of austenitic stainless steel materials. To fully obtain these effects, the Mo content is set to 0.10 mass% or more, preferably 0.15 mass% or more. On the other hand, if the Mo content is too high, the δ ferrite phase is easily generated, making it impossible to achieve low magnetic or non-magnetic properties. Therefore, the Mo content is set to 1.50 mass% or less, preferably 1.45 mass% or less.
Ｃａは、不可避的不純物として含まれ得るＳを硫化物として固定し、熱間加工性を向上させる元素である。この作用を十分に得るためには、Ｃａ含有量を０．０００５質量％以上、好ましくは０．００１０質量％以上とする。一方、Ｃａ含有量が多すぎると、靭性、延性及び清浄性が低下する。そのため、Ｃａ含有量は、０．０１５０質量％以下、好ましくは０．０１００質量％以下とする。 Ca is an element that fixes S, which may be contained as an unavoidable impurity, as sulfides, improving hot workability. To fully obtain this effect, the Ca content is set to 0.0005 mass% or more, preferably 0.0010 mass% or more. On the other hand, if the Ca content is too high, toughness, ductility, and cleanliness decrease. Therefore, the Ca content is set to 0.0150 mass% or less, preferably 0.0100 mass% or less.
Ｖ、Ｎｂ及びＴｉは、加工硬化能を高める作用を有する元素である。ただし、これらの元素の含有量が多すぎると、δフェライト相が生成し易くなり、低磁性又は非磁性とすることができなくなる。そのため、Ｖ、Ｎｂ及びＴｉの含有量は、それぞれ０．３５質量％以下とすることが好ましい。一方、Ｖ、Ｎｂ及びＴｉの含有量の下限は、特に限定されないが、上記の作用を安定して得る観点から、それぞれ０．１０質量％以上とすることが好ましい。 V, Nb and Ti are elements that have the effect of increasing work hardening ability. However, if the content of these elements is too high, the δ ferrite phase is easily generated, and it becomes impossible to obtain low magnetic or non-magnetic properties. Therefore, it is preferable that the content of V, Nb and Ti is 0.35 mass% or less, respectively. On the other hand, the lower limit of the content of V, Nb and Ti is not particularly limited, but from the viewpoint of stably obtaining the above-mentioned effects, it is preferable that each be 0.10 mass% or more.
Ｃ及びＮの合計含有量は、オーステナイト系ステンレス鋼材のばね性と関係する。ばね性（弾性限界応力）の評価指標である「０．０１％耐力」を向上させるためには、Ｃ及びＮの合計含有量を十分に確保する必要がある。そのため、良好なばね性、特に０．０１％耐力を５００Ｎ／ｍｍ2以上を得るためには、Ｃ及びＮの合計含有量を０．２５質量％以上とする。一方、Ｃ及びＮの合計量の上限は、特に限定されないが、好ましくは０．３４０質量％以下、より好ましくは０．３３０質量％以下である。 The total content of C and N is related to the springiness of the austenitic stainless steel material. In order to improve the "0.01% yield strength", which is an evaluation index of the springiness (elastic limit stress), it is necessary to ensure a sufficient total content of C and N. Therefore, in order to obtain good springiness, particularly a 0.01% yield strength of 500 N/mm2 or more, the total content of C and N is set to 0.25 mass% or more. On the other hand, the upper limit of the total amount of C and N is not particularly limited, but is preferably 0.340 mass% or less, more preferably 0.330 mass% or less.
本発明の実施形態に係るオーステナイト系ステンレス鋼材は、下記式（１）で表されるＭＤ値が－７０以下、好ましくは－７１以下に制御される。
ＭＤ＝５５１－４６２（Ｃ＋Ｎ）－９．２Ｓｉ－１９．１Ｍｎ－２９（Ｎｉ＋Ｃｕ）－１３．７Ｃｒ－１８．５Ｍｏ （１）
式（１）中、各元素記号は各元素の含有量（質量％）である。
ここで、式（１）で定義されるＭＤ値は、加工誘起マルテンサイト相の生成し易さを表す指標である。ＭＤ値が低いほど、加工誘起マルテンサイト相が生成し難く、調質圧延などの加工後に安定して低磁性又は非磁性を実現する上で有利となる。
本発明の実施形態に係るオーステナイト系ステンレス鋼材は、ＭＤ値を－７０以下に制御することにより、加工誘起マルテンサイト相の量（以下、「加工誘起マルテンサイト量」という）を少なくし（特に、６．０体積％以下に調整し）、低磁性又は非磁性を実現することができる。なお、ＭＤ値の下限は、特に限定されないが、好ましくは－２２０以上、より好ましくは－２００以上、さらに好ましくは－１５０以上である。
In the austenitic stainless steel material according to the embodiment of the present invention, the MD value represented by the following formula (1) is controlled to be −70 or less, preferably −71 or less.
MD = 551 - 462 (C + N) - 9.2 Si - 19.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo (1)
In formula (1), each element symbol represents the content (mass %) of each element.
Here, the MD value defined by formula (1) is an index representing the ease of formation of the deformation-induced martensite phase. The lower the MD value, the more difficult it is for the deformation-induced martensite phase to form, which is advantageous in achieving stable low magnetic or non-magnetic properties after processing such as temper rolling.
In the austenitic stainless steel material according to the embodiment of the present invention, the amount of deformation-induced martensite phase (hereinafter referred to as "deformation-induced martensite amount") is reduced (particularly adjusted to 6.0 volume % or less) by controlling the MD value to -70 or less, and low magnetic or non-magnetic properties can be achieved. The lower limit of the MD value is not particularly limited, but is preferably -220 or more, more preferably -200 or more, and even more preferably -150 or more.
本発明の実施形態に係るオーステナイト系ステンレス鋼材は、下記式（２）で表されるδｃａｌ値が３．２０以下、好ましくは３．００以下、より好ましくは２．００以下である。
δｃａｌ＝－１５－４４．９１Ｃ－０．８８Ｍｎ－２．３１Ｎｉ＋２．２Ｃｒ－１．０８Ｃｕ－２８．８Ｎ （２）
式（２）中、各元素記号は各元素の含有量（質量％）である。
ここで、式（２）で定義されるδｃａｌ値は、連続鋳造で製造したスラブ（鋳片）を１２３０℃で２時間加熱した後の、スラブの厚さ中央部におけるδフェライト相の量（以下、「δフェライト量」という）を表す指標である。スラブに存在するδフェライト量が多すぎると、その後の工程（圧延工程など）で完全に消失させることが困難となる場合があり、低磁性又は非磁性の実現に支障となる。また、スラブにおけるδフェライト量は、熱間加工性にも大きく影響する。例えば、Ｍｎ及びＣｕの含有量が多い組成系では、スラブの加熱時にＣｕ－Ｍｎ相が析出し易くなる。このＣｕ－Ｍｎ相は融点が低く、熱間圧延温度域で脆弱であるため、熱間圧延時に「二枚割れ」が発生する要因となる。このＣｕ－Ｍｎ相の析出量はδフェライト量と相関があり、δフェライト量が多くなるにつれてＣｕ－Ｍｎ相の析出量が増大する。また、δフェライト量が少なすぎると、熱間圧延時に表面にヘゲ疵や板幅方向端部に耳割れも発生し易くなる。
本発明の実施形態に係るオーステナイト系ステンレス鋼材は、δｃａｌ値を３．２０以下に制御することにより、スラブに存在するδフェライト量を適切な範囲に調整し、低磁性又は非磁性を実現するとともに、熱間加工性を向上させ、二枚割れ、ヘゲ疵、耳割れなどの欠陥を生じ難くすることができる。なお、δｃａｌ値の下限は、特に限定されないが、好ましくは－１１以上、より好ましくは－１０以上、さらに好ましくは－９以上である。
The austenitic stainless steel material according to the embodiment of the present invention has a δcal value represented by the following formula (2) of 3.20 or less, preferably 3.00 or less, and more preferably 2.00 or less.
δcal = -15-44.91C-0.88Mn-2.31Ni+2.2Cr-1.08Cu-28.8N (2)
In formula (2), each element symbol represents the content (mass %) of each element.
Here, the δcal value defined by formula (2) is an index representing the amount of δ ferrite phase (hereinafter referred to as "δ ferrite amount") in the thickness center of the slab after heating the slab (cast piece) produced by continuous casting at 1230 ° C for 2 hours. If the amount of δ ferrite present in the slab is too much, it may be difficult to completely eliminate it in the subsequent process (rolling process, etc.), which will hinder the realization of low magnetism or non-magnetism. In addition, the amount of δ ferrite in the slab also greatly affects hot workability. For example, in a composition system with a high content of Mn and Cu, the Cu-Mn phase is likely to precipitate when the slab is heated. This Cu-Mn phase has a low melting point and is brittle in the hot rolling temperature range, which is a factor in the occurrence of "two-piece cracking" during hot rolling. The amount of precipitation of this Cu-Mn phase is correlated with the amount of δ ferrite, and the amount of precipitation of the Cu-Mn phase increases as the amount of δ ferrite increases. Furthermore, if the amount of δ ferrite is too small, scabs are likely to occur on the surface and edge cracks are likely to occur at the ends in the width direction of the sheet during hot rolling.
In the austenitic stainless steel material according to the embodiment of the present invention, by controlling the δcal value to 3.20 or less, the amount of δ ferrite present in the slab can be adjusted to an appropriate range, low magnetism or non-magnetism can be realized, hot workability can be improved, and defects such as splitting in two, scab defects, edge cracks, etc. can be made less likely to occur. The lower limit of the δcal value is not particularly limited, but is preferably -11 or more, more preferably -10 or more, and even more preferably -9 or more.
本発明の実施形態に係るオーステナイト系ステンレス鋼材の形態は、鋼板、鋳造品などの様々な形態とすることができるが、好ましくは鋼板、より好ましくは冷延鋼板である。
オーステナイト系ステンレス鋼材の厚さは、用途に応じて適宜調整すればよいが、好ましくは０．０２～１．５ｍｍである。
The austenitic stainless steel material according to the embodiment of the present invention may be in various forms such as a steel plate or a casting, but is preferably a steel plate, more preferably a cold-rolled steel plate.
The thickness of the austenitic stainless steel material may be appropriately adjusted depending on the application, but is preferably 0.02 to 1.5 mm.
上記のような特徴を有する本発明の実施形態に係るオーステナイト系ステンレス鋼材は、低磁性又は非磁性であるとともに、強度、延性及びばね性に優れている。そのため、特に薄肉化が要求されている電子機器部材（例えば、筐体、部品など）の材料として好適に用いることができ、電子機器部材の小型化及び軽量化を達成することができる。 The austenitic stainless steel material according to the embodiment of the present invention, which has the above-mentioned characteristics, is low magnetic or non-magnetic, and has excellent strength, ductility, and springiness. Therefore, it can be suitably used as a material for electronic device components (e.g., housings, parts, etc.) that require thinning, and can achieve miniaturization and weight reduction of electronic device components.
本発明の実施形態に係るオーステナイト系ステンレス鋼材は、一般的なステンレス鋼板の大量生産設備などを用い、当該技術分野において公知の方法に準じて製造することができる。例えば、本発明の実施形態に係るオーステナイト系ステンレス鋼材が冷延鋼板である場合、連続鋳造で得られたスラブを熱間圧延した後、冷間圧延することによって製造することができる。熱間圧延及び冷間圧延は、当該技術分野において公知の方法に準じて行うことができる。また、熱間圧延後及び冷間圧延後には、焼鈍及び酸洗などの公知の工程を実施してもよい。 The austenitic stainless steel material according to the embodiment of the present invention can be manufactured in accordance with a method known in the art using general mass production equipment for stainless steel sheets. For example, when the austenitic stainless steel material according to the embodiment of the present invention is a cold-rolled steel sheet, it can be manufactured by hot rolling a slab obtained by continuous casting and then cold rolling it. The hot rolling and cold rolling can be performed in accordance with a method known in the art. In addition, after the hot rolling and cold rolling, known processes such as annealing and pickling may be performed.
また、本発明の実施形態に係るオーステナイト系ステンレス鋼材は、組成を制御することによって熱間加工性を向上させているため、熱間圧延において１ヒート圧延を行うことができる。すなわち、本発明の実施形態に係るオーステナイト系ステンレス鋼材は、Ｃ：０．０９５質量％超過０．１６０質量％以下、Ｓｉ：０．２０～１．２０質量％、Ｍｎ：２．００～６．００質量％、Ｎｉ：２．５０～６．００質量％、Ｃｒ：１４．００～１９．５０質量％、Ｎ：０．０９０～０．２１０質量％、Ｃｕ：０．５０～３．６０質量％、Ｍｏ：０．１０～１．５０質量％、Ｃａ：０．０００５～０．０１５０質量％を含み、残部がＦｅ及び不可避的不純物からなり、Ｃ及びＮの合計含有量が０．２５質量％以上、下記式（１）で表されるＭＤ値が－７０以下、及び下記式（２）で表されるδｃａｌ値が３．２０以下であるスラブを１１８０℃以上に加熱して１ヒート圧延する熱間圧延を行うことによって製造することができる。
ＭＤ＝５５１－４６２（Ｃ＋Ｎ）－９．２Ｓｉ－１９．１Ｍｎ－２９（Ｎｉ＋Ｃｕ）－１３．７Ｃｒ－１８．５Ｍｏ （１）
δｃａｌ＝－１５－４４．９１Ｃ－０．８８Ｍｎ－２．３１Ｎｉ＋２．２Ｃｒ－１．０８Ｃｕ－２８．８Ｎ （２）
式（１）及び（２）中、各元素記号は各元素の含有量（質量％）である。
したがって、この製造方法は、２ヒート圧延（約８５０℃の低温で分塊圧延を行った後に仕上圧延を行う圧延）に比べて生産性を高めることができ、しかも二枚割れ、ヘゲ疵、耳割れなどの欠陥も生じ難い。
Furthermore, since the austenitic stainless steel material according to the embodiment of the present invention has improved hot workability by controlling the composition, one-heat rolling can be performed in the hot rolling. That is, the austenitic stainless steel material according to the embodiment of the present invention contains C: more than 0.095 mass% and 0.160 mass% or less, Si: 0.20 to 1.20 mass%, Mn: 2.00 to 6.00 mass%, Ni: 2.50 to 6.00 mass%, Cr: 14.00 to 19.50 mass%, N: 0.090 to 0.210 mass%, Cu: 0.50 to 3.60 mass%, Mo: 0.10 to 1.50 mass%, Ca: 0.0005 to 0.0150 mass%, the balance being Fe and inevitable impurities. The total content of C and N is 0.25 mass% or more, the MD value represented by the following formula (1) is -70 or less, and the δcal value represented by the following formula (2) is 3.20 or less. It can be produced by heating a slab to 1180 ° C. or more and performing hot rolling by rolling it once.
MD = 551 - 462 (C + N) - 9.2 Si - 19.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo (1)
δcal = -15-44.91C-0.88Mn-2.31Ni+2.2Cr-1.08Cu-28.8N (2)
In formulas (1) and (2), each element symbol represents the content (mass %) of each element.
Therefore, this manufacturing method can improve productivity compared to two-heat rolling (rolling in which blooming is performed at a low temperature of about 850°C followed by finish rolling), and also reduces the occurrence of defects such as splitting, scabs, and edge cracks.
熱間圧延後には、冷間圧延及び焼鈍を行い、次いで２０～５０％の圧延率で調質圧延を行うことが好ましい。このような圧延率で調質圧延を行うことにより、最終厚さが０．０２ｍｍ～１．５ｍｍの冷延鋼板を得ることができる。 After hot rolling, it is preferable to perform cold rolling and annealing, and then temper rolling at a rolling ratio of 20 to 50%. By performing temper rolling at such a rolling ratio, a cold-rolled steel sheet with a final thickness of 0.02 mm to 1.5 mm can be obtained.
上記のような本発明の実施形態に係るオーステナイト系ステンレス鋼材の製造方法は、１ヒート圧延する熱間圧延を行うことができるため、生産性が高く、二枚割れ、ヘゲ疵、耳割れなどの欠陥も生じ難い。そのため、この製造方法は、歩留りの向上、後工程の負荷及び製造コストの低減に寄与するだけでなく、製品特性を安定化させることが可能となる。 The manufacturing method of the austenitic stainless steel material according to the embodiment of the present invention described above is highly productive because it can perform hot rolling in one heat, and defects such as splitting, scabs, and edge cracks are unlikely to occur. Therefore, this manufacturing method not only contributes to improving yields and reducing the burden on subsequent processes and manufacturing costs, but also makes it possible to stabilize product characteristics.
本発明の実施形態に係る電子機器部材は、上記のオーステナイト系ステンレス鋼材から形成されている。上記のオーステナイト系ステンレス鋼材は、低磁性又は非磁性であるとともに強度、延性及びばね性に優れており、薄肉化することができるため、電子機器部材を小型化及び軽量化することができる。
電子機器部材としては、特に限定されないが、磁化され難い性質が要求される部材であることが好ましい。電子機器部材の例としては、電子機器を構成する筐体、部品などが挙げられる。
The electronic device member according to the embodiment of the present invention is formed from the above-mentioned austenitic stainless steel material. The above-mentioned austenitic stainless steel material is low magnetic or non-magnetic, has excellent strength, ductility and springiness, and can be made thin, so that the electronic device member can be made smaller and lighter.
The electronic device member is not particularly limited, but is preferably a member that is required to have a property of being difficult to magnetize. Examples of the electronic device member include a housing and parts that constitute an electronic device.
以下に、実施例を挙げて本発明の内容を詳細に説明するが、本発明はこれらに限定して解釈されるものではない。 The present invention will be described in detail below with reference to examples, but the present invention should not be construed as being limited to these.
表１に示す組成のインゴットを溶製し、熱間圧延、焼鈍、酸洗、冷間圧延、焼鈍、酸洗及び調質圧延を順次行い、オーステナイト系ステンレス冷延鋼板（全てのサンプルにおいて板厚０．２ｍｍとした）を得た。全てのサンプルにおいて、熱間圧延は、スラブを１２３０℃に加熱した後、１ヒート圧延することによって行った。１ヒート圧延は、パス数を１０回とし、圧延率を９５％とした。発明鋼の調質圧延は、表２に示す圧延率で実施した。なお、圧延率は下記式（３）で表すことができる。
圧延率（％）＝（ｈ0－ｈ1）ｈ0×１００ （３）
式中、ｈ0は圧延前の板厚（ｍｍ）、ｈ1は圧延後の板厚（ｍｍ）である。
また、比較鋼については、３／４Ｈ仕上げ相当に調質した。
Ingots having the compositions shown in Table 1 were melted, and hot rolling, annealing, pickling, cold rolling, annealing, pickling and temper rolling were successively performed to obtain austenitic stainless cold-rolled steel sheets (all samples had a sheet thickness of 0.2 mm). In all samples, hot rolling was performed by heating the slab to 1230°C and then rolling it once. The number of passes in one heat rolling was 10, and the rolling reduction was 95%. The temper rolling of the inventive steel was performed at the rolling reduction shown in Table 2. The rolling reduction can be expressed by the following formula (3).
Rolling ratio (%) = (h 0 -h 1 ) h 0 × 100 (3)
In the formula, h0 is the plate thickness before rolling (mm), and h1 is the plate thickness after rolling (mm).
The comparative steel was also tempered to a 3/4H finish.
上記で得られたオーステナイト系ステンレス冷延鋼板及びその製造工程中に得られた中間材について以下の評価を行った。 The following evaluations were carried out on the austenitic stainless steel cold rolled sheet obtained above and the intermediate material obtained during the manufacturing process.
（１）硬さ
オーステナイト系ステンレス冷延鋼板の圧延面を＃６００の研磨材で研磨した表面についてＪＩＳ Ｚ２２４４：２００９に従って、ビッカース硬さの測定（ＨＶ２０）を行った。測定は、任意の５箇所で行い、その平均値を評価結果とした。
なお、ビッカース硬さが３２０ＨＶ以上、好ましくは３４５以上である場合に、強度が良好であると判断することができる。
(1) Hardness The rolled surface of the austenitic stainless steel cold-rolled steel sheet was polished with a #600 abrasive and the Vickers hardness (HV20) was measured according to JIS Z2244: 2009. The measurement was performed at any five points, and the average value was used as the evaluation result.
In addition, when the Vickers hardness is 320 HV or more, preferably 345 or more, it can be determined that the strength is good.
（２）引張試験
オーステナイト系ステンレス冷延鋼板から圧延方向が引張方向となるようにＪＩＳ １３Ｂ号試験片を採取した後、ＪＩＳ Ｚ２２４１：２０１１による引張試験を行い、０．２％耐力、引張強さ及び破断伸びを求めた。０．２％耐力、引張強さ及び破断伸びは、３つの試験片で測定し、その平均値を測定結果とした。
また、上記と同じようにして作製したＪＩＳ １３Ｂ号試験片を用い、引張速度５ｍｍ／分にて引張試験を行って得られた公称応力－ひずみ曲線から、オフセット法にて０.０１％耐力を求めた。
なお、０．２％耐力が８００Ｎ／ｍｍ2以上、好ましくは９００Ｎ／ｍｍ2以上、引張強さが９００Ｎ／ｍｍ2以上、好ましくは１０００Ｎ／ｍｍ2以上、破断伸びが１０％以上、好ましくは１１％以上である場合に、延性が良好であると判断することができる。また、０．０１％耐力が５００Ｎ／ｍｍ2以上、好ましくは５５０Ｎ／ｍｍ2以上である場合に、ばね性が良好であると判断することができる。
(2) Tensile test JIS No. 13B test pieces were taken from the austenitic stainless steel cold-rolled steel sheet so that the rolling direction was the tensile direction, and then a tensile test was carried out according to JIS Z2241: 2011 to determine the 0.2% yield strength, tensile strength, and breaking elongation. The 0.2% yield strength, tensile strength, and breaking elongation were measured for three test pieces, and the average values were used as the measurement results.
Further, a tensile test was carried out at a tensile speed of 5 mm/min using a JIS No. 13B test piece prepared in the same manner as above, and the 0.01% proof stress was determined from the nominal stress-strain curve obtained by the offset method.
In addition, when the 0.2% proof stress is 800 N/ mm2 or more, preferably 900 N/ mm2 or more, the tensile strength is 900 N/ mm2 or more, preferably 1000 N/ mm2 or more, and the breaking elongation is 10% or more, preferably 11% or more, the ductility can be judged to be good. In addition, when the 0.01% proof stress is 500 N/mm2 or more, preferably 550 N/ mm2 or more, the spring property can be judged to be good.
（３）加工誘起マルテンサイト量
オーステナイト系ステンレス冷延鋼板から２５ｍｍ×２５ｍｍの試験片を５枚採取し、それら５枚の試験片を積層した状態で、フェライトスコープ（フィッシャー社製）を用いて磁性相であるマルテンサイト相の量を測定することによって、加工誘起マルテンサイト量を定めた。
(3) Amount of deformation-induced martensite Five test pieces measuring 25 mm × 25 mm were taken from the austenitic stainless cold-rolled steel sheet, and the five test pieces were stacked together. The amount of the martensite phase, which is a magnetic phase, was measured using a Ferrite Scope (manufactured by Fisher Scientific) to determine the amount of deformation-induced martensite.
（４）磁性
オーステナイト系ステンレス冷延鋼板から直径５ｍｍ、板厚０．２ｍｍの試験片を５枚採取し、それら５枚の試験片を積層した状態で、試料振動型磁力計（理研電子株式会社製、ＢＨＶ５２５）を用いて掃引速度１ｋＯｅ（７９.５８ｋＡ／ｍ）／分で１ｋＯｅ（７９.５８ｋＡ／ｍ）の磁場を加えて磁化させ、そこで得られた磁場－磁化曲線の傾きより透磁率を求め、真空の透磁率４π×１０-7Ｈ／ｍで除して比透磁率とした。透磁率の測定は５つの試験片で行い、各試験片で算出された比透磁率の平均値を測定結果とした。
なお、比透磁率は、１．１０以下であれば非磁性（μ≦１．０１）又は低磁性（１．０１＜μ≦１．１０）であると判断することができる。
(4) Magnetism Five test pieces with a diameter of 5 mm and a thickness of 0.2 mm were taken from an austenitic stainless steel cold-rolled steel sheet, and these five test pieces were stacked together and magnetized by applying a magnetic field of 1 kOe (79.58 kA/m) at a sweep rate of 1 kOe (79.58 kA/m)/min using a sample vibration magnetometer (Riken Denshi Co., Ltd., BHV525). The magnetic permeability was calculated from the slope of the magnetic field-magnetization curve obtained, and the relative magnetic permeability was calculated by dividing the magnetic permeability in vacuum, 4π×10 −7 H/m. The magnetic permeability was measured for five test pieces, and the average of the relative magnetic permeabilities calculated for each test piece was used as the measurement result.
If the relative permeability is 1.10 or less, it can be determined that the material is non-magnetic (μ≦1.01) or low-magnetic (1.01<μ≦1.10).
（５）耳割れ及びヘゲ疵
熱間圧延後の中間材（熱延材）において、熱延材の表面におけるヘゲ疵の有無、熱延材の板幅方向端部における耳割れの有無を目視にて評価した。この評価において、ヘゲ疵又は耳割れが無かったものを〇、ヘゲ疵又は耳割れがあったものを×と表す。
(5) Edge cracks and scabs The intermediate material (hot-rolled material) after hot rolling was visually evaluated for the presence or absence of scabs on the surface of the hot-rolled material and the presence or absence of edge cracks at the ends in the sheet width direction of the hot-rolled material. In this evaluation, a material without scabs or edge cracks was indicated as ◯, and a material with scabs or edge cracks was indicated as ×.
（６）熱間加工性
熱間圧延後の中間材（熱延材）から外径１０ｍｍ、長さ１２０ｍｍの試験片を採取し、グリーブル試験を行った。グリーブル試験は、次のようにして行った。まず、試験片を１１８０℃まで５０℃／ｓで昇温して５分間保持した。次に、試験片を試験温度まで５０℃／ｓで冷却して５分間保持した後、ひずみ速度１０／ｓで引張試験を行った。ここで、試験温度は９００～１１５０℃の範囲で５０℃間隔の６条件にて行い、それぞれの絞り値を求めた。評価には１０００℃における絞り値を採用した。
なお、１０００℃は、鋼材に不可避的不純物として含まれるＳが結晶粒界に偏析することで結晶粒界を低下させ、粒界割れが生じ易くなる温度である。したがって、１０００℃の絞り値が６０以上である場合に、熱間加工性が良好であると判断することができる。
上記の評価結果を表２に示す。
(6) Hot workability A test piece with an outer diameter of 10 mm and a length of 120 mm was taken from the intermediate material (hot-rolled material) after hot rolling, and a Gleeble test was performed. The Gleeble test was performed as follows. First, the test piece was heated to 1180°C at 50°C/s and held for 5 minutes. Next, the test piece was cooled to the test temperature at 50°C/s and held for 5 minutes, and then a tensile test was performed at a strain rate of 10/s. Here, the test temperature was in the range of 900 to 1150°C, and six conditions were performed at 50°C intervals, and the reduction of area was obtained for each. The reduction of area at 1000°C was used for evaluation.
In addition, 1000°C is the temperature at which S contained as an inevitable impurity in the steel material segregates at the grain boundaries, weakening the grain boundaries and making the steel more susceptible to grain boundary cracking. Therefore, when the reduction of area at 1000°C is 60 or more, it can be determined that the hot workability is good.
The above evaluation results are shown in Table 2.
表２に示されるように、発明鋼Ａ１～Ａ１７は、全ての評価結果が良好であり、低磁性又は非磁性であるとともに、強度、延性及びばね性に優れ、且つ熱間加工性が良好で耳割れやヘゲ疵の発生を抑制し得ることが確認された。
これに対して比較鋼Ｂ１～Ｂ７は、組成、ＭＤ値及びδｃａｌ値の１つ以上が所定の範囲外であったため、いくつかの評価結果が良好でなかった。
As shown in Table 2, the inventive steels A1 to A17 had good evaluation results in all cases, and were low magnetic or non-magnetic. They also had excellent strength, ductility, and spring properties, and had good hot workability and were able to suppress the occurrence of edge cracks and scabs.
In contrast, in the comparative steels B1 to B7, one or more of the composition, MD value, and δcal value were outside the prescribed range, and therefore some of the evaluation results were not good.
以上の結果からわかるように、本発明によれば、低磁性又は非磁性であるとともに、強度、延性及びばね性に優れ、しかも生産性が高いオーステナイト系ステンレス鋼材及びその製造方法を提供することができる。また、本発明によれば、小型化及び軽量化が可能な電子機器部材を提供することができる。 As can be seen from the above results, the present invention can provide an austenitic stainless steel material and a manufacturing method thereof that is low magnetic or non-magnetic, has excellent strength, ductility, and springiness, and is highly productive. Furthermore, the present invention can provide electronic device components that can be made smaller and lighter.
Claims (7)
ＭＤ＝５５１－４６２（Ｃ＋Ｎ）－９．２Ｓｉ－１９．１Ｍｎ－２９（Ｎｉ＋Ｃｕ）－１３．７Ｃｒ－１８．５Ｍｏ （１）
δｃａｌ＝－１５－４４．９１Ｃ－０．８８Ｍｎ－２．３１Ｎｉ＋２．２Ｃｒ－１．０８Ｃｕ－２８．８Ｎ （２）
式（１）及び（２）中、各元素記号は各元素の含有量（質量％）である。 An austenitic stainless steel material comprising: C: more than 0.095 mass% and 0.160 mass% or less; Si: 0.20 to 1.20 mass%; Mn: 2.00 to 6.00 mass%; Ni: 2.50 to 6.00 mass%; Cr: 14.00 to 19.50 mass%; N: 0.090 to 0.210 mass%; Cu: 0.50 to 3.60 mass%; Mo: 0.10 to 1.50 mass%; Ca: 0.0010 to 0.0150 mass%; the balance being Fe and unavoidable impurities; the total content of C and N is 0.25 mass% or more; an MD value represented by the following formula (1) is -70 or less; and a δcal value represented by the following formula (2) is -11 to 3.20.
MD = 551 - 462 (C + N) - 9.2 Si - 19.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo (1)
δcal = -15-44.91C-0.88Mn-2.31Ni+2.2Cr-1.08Cu-28.8N (2)
In formulas (1) and (2), each element symbol represents the content (mass %) of each element.
ＭＤ＝５５１－４６２（Ｃ＋Ｎ）－９．２Ｓｉ－１９．１Ｍｎ－２９（Ｎｉ＋Ｃｕ）－１３．７Ｃｒ－１８．５Ｍｏ （１）
δｃａｌ＝－１５－４４．９１Ｃ－０．８８Ｍｎ－２．３１Ｎｉ＋２．２Ｃｒ－１．０８Ｃｕ－２８．８Ｎ （２）
式（１）及び（２）中、各元素記号は各元素の含有量（質量％）である。 A method for producing an austenitic stainless steel material, comprising: C: more than 0.095 mass% and 0.160 mass% or less; Si: 0.20 to 1.20 mass%; Mn: 2.00 to 6.00 mass%; Ni: 2.50 to 6.00 mass%; Cr: 14.00 to 19.50 mass%; N: 0.090 to 0.210 mass%; Cu: 0.50 to 3.60 mass%; Mo: 0.10 to 1.50 mass%; Ca: 0.0010 to 0.0150 mass%; the balance being Fe and unavoidable impurities; C and N: a total content of 0.25 mass% or more; an MD value represented by the following formula (1) of -70 or less; and a δcal value represented by the following formula (2) of -11 to 3.20; and heating the slab to 1180°C or more and performing one-heat hot rolling.
MD = 551 - 462 (C + N) - 9.2 Si - 19.1 Mn - 29 (Ni + Cu) - 13.7 Cr - 18.5 Mo (1)
δcal = -15-44.91C-0.88Mn-2.31Ni+2.2Cr-1.08Cu-28.8N (2)
In formulas (1) and (2), each element symbol represents the content (mass %) of each element.
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| JP2005298932A (en) | 2004-04-14 | 2005-10-27 | Nippon Steel & Sumikin Stainless Steel Corp | Metastable austenitic stainless steel wire used for high strength steel wire for spring excellent in rigidity |
| JP2010138419A (en) | 2008-12-09 | 2010-06-24 | Sanyo Special Steel Co Ltd | Austenitic stainless steel excellent in hot workability |
| CN102337481A (en) | 2010-07-20 | 2012-02-01 | 宝山钢铁股份有限公司 | Molybdenum-containing nickel-saving austenitic stainless steel with excellent corrosion resistance and manufacturing method thereof |
| JP2012172211A (en) | 2011-02-22 | 2012-09-10 | Nisshin Steel Co Ltd | METHOD OF MANUFACTURING LOW Ni AUSTENITIC STAINLESS STEEL SHEET |
| JP2014189833A (en) | 2013-03-27 | 2014-10-06 | Nippon Steel & Sumikin Stainless Steel Corp | High strength austenitic free-cutting stainless steel wire and method of producing the same |
| JP2018145487A (en) | 2017-03-07 | 2018-09-20 | 日新製鋼株式会社 | Low magnetic austenite stainless steel and cold rolled steel sheet |
| WO2019240127A1 (en) | 2018-06-11 | 2019-12-19 | 日鉄ステンレス株式会社 | Wire rod for stainless steel wire, stainless steel wire and manufacturing method therefor, and spring component |
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2020
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005298932A (en) | 2004-04-14 | 2005-10-27 | Nippon Steel & Sumikin Stainless Steel Corp | Metastable austenitic stainless steel wire used for high strength steel wire for spring excellent in rigidity |
| JP2010138419A (en) | 2008-12-09 | 2010-06-24 | Sanyo Special Steel Co Ltd | Austenitic stainless steel excellent in hot workability |
| CN102337481A (en) | 2010-07-20 | 2012-02-01 | 宝山钢铁股份有限公司 | Molybdenum-containing nickel-saving austenitic stainless steel with excellent corrosion resistance and manufacturing method thereof |
| JP2012172211A (en) | 2011-02-22 | 2012-09-10 | Nisshin Steel Co Ltd | METHOD OF MANUFACTURING LOW Ni AUSTENITIC STAINLESS STEEL SHEET |
| JP2014189833A (en) | 2013-03-27 | 2014-10-06 | Nippon Steel & Sumikin Stainless Steel Corp | High strength austenitic free-cutting stainless steel wire and method of producing the same |
| JP2018145487A (en) | 2017-03-07 | 2018-09-20 | 日新製鋼株式会社 | Low magnetic austenite stainless steel and cold rolled steel sheet |
| WO2019240127A1 (en) | 2018-06-11 | 2019-12-19 | 日鉄ステンレス株式会社 | Wire rod for stainless steel wire, stainless steel wire and manufacturing method therefor, and spring component |
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